Project 2: Oldest-Old Mortality and Disability Among Danish Twins This research project is designed to extend the Danish Twin Register in three directions, involving different-sex DZ twins, causes of death, and ADLs. The new data will be carefully checked, achieved, and published in full to aid other researchers. In addition, the new data, together with existing data, will be analyzed to better understand genetic factors underlying trajectories of mortality. Specifically, we will: Update and computerized data on different-sex DZ twins born between 1870 and 1910, merge these data with the existing data base on MZ and same-sex DZ twins, and then analyze these data to better understand mortality patterns for men vs. women, as well as studying special characteristics of different-sex DZ twins compared with same-sex MZ and DZ twins. Link the Danish Twin Register with the Danish Cause-of-Death Register to obtain proximate, underlying, and contribute causes of death for all twins who died since 2943, and then analyze these data to uncover genetic factors and common-childhood-environment factors underlying causes (or groups of causes) of death that are correlated for MZ and DZ twins. Collect and computerize data on the health and disability of elderly Danish twins in 1995 and again two years later, and then analyze these data to uncover genetic factors and common-childhood-environment factors underlying health and disability patterns and subsequently mortality.